Azure Cosmos DB vs VerneMQ: What are the differences?

# Introduction

1. **Data Model**: Azure Cosmos DB is a globally distributed, multi-model database service that allows you to interact with data using various APIs including SQL, MongoDB, Cassandra, etc. On the other hand, VerneMQ is an open-source, distributed MQTT message broker that specializes in handling real-time messaging and IoT data.
2. **Use Cases**: Azure Cosmos DB is commonly used for globally distributed applications that require low latency and high availability, while VerneMQ is preferred for applications that rely on MQTT protocol for real-time communication such as IoT devices, telemetry, and messaging systems.
3. **Consistency Model**: In Azure Cosmos DB, you can choose from different consistency levels (strong, bounded staleness, session, consistent prefix, eventual) based on your application requirements. VerneMQ follows the eventual consistency model where data consistency is eventually guaranteed but may experience temporary inconsistencies during synchronization.
4. **Scalability**: Azure Cosmos DB offers horizontal scalability with automatic partitioning and multi-master replication across multiple regions globally. VerneMQ also supports horizontal scalability through clustering but may require manual configuration and maintenance for scaling-out.
5. **Query Language**: Azure Cosmos DB supports SQL-like query language for querying data across different data models, whereas VerneMQ focuses more on message routing and processing rather than supporting complex querying capabilities.
6. **Pricing Model**: Azure Cosmos DB is a fully managed cloud service by Microsoft with a pay-as-you-go pricing model based on the provisioned throughput and storage consumed. VerneMQ, being open-source, requires self-hosting and management, resulting in lower costs but potentially higher operational overhead.

In Summary, Azure Cosmos DB and VerneMQ differ in terms of their data model, use cases, consistency model, scalability, query language support, and pricing model.